There is a big collision threat in companies using forklifts, especially around traffic strip doors or flexible swing doors. These kinds of doors are opened directly in response to an approaching forklift, and close automatically. When too many forklifts are operated at the same time, there is a threat especially when two of the forklifts are going towards the same door coming from different directions. However, in numerous companies, traffic through the same door by both people and moving forklifts in necessary, and the collision threat in this situation is substantial.
Thus, to alleviate collision threat, there is a need for a measuring system and method to measure a distance between two points and providing an indication if the distance is within a predetermined distance.